Muscle Mass During Space Exploration

This study has been completed.

Sponsor:

The University of Texas Medical Branch, Galveston

ClinicalTrials.gov Identifier:

NCT00968344

First Posted: August 31, 2009

Last Update Posted: May 28, 2015

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Bedrest will blunt the anabolic response to a mixed nutrient meal, facilitating a loss of muscle mass and functional capacity that is only partially restored during rehabilitation.

Enriching daily meals with leucine will promote protein synthesis and maintain the anabolic response to mixed nutrient meal ingestion. This will preserve lean muscle mass and function during bedrest and facilitate the recovery of functional and metabolic capacity during rehabilitation.

Our long-term goal is to identify, prevent and remedy defects in the metabolic pathway that contribute to the loss of muscle mass and function during exposure to microgravity. Demographic data indicate that the average age of shuttle crew members has increased from 40.7 yrs in 1995 to 46.7 yrs in 2007 with an increasing number of astronauts over 50 yrs of age. We contend that the loss of muscle mass and function during spaceflight is facilitated by an age-associated, progressive impairment in the ability to mount an anabolic response to standard mixed nutrient meals. We propose that enriching daily meals with a low-volume leucine supplement will reduce the deleterious effects of microgravity on skeletal muscle and facilitate recovery during rehabilitation.

We will employ our established 14 day bed rest protocol to model the skeletal muscle unloading that occurs during microgravity. We will also examine recovery of muscle mass and functional capacity during a 7 day rehabilitation period. We will study 2 groups: CON (Bedrest/Recovery + Placebo; n=15), LEU (Bedrest/Recovery + Leucine; n=15). We will assess a) markers of translation initiation, b) muscle protein synthesis, c) muscle mass and body composition and d) strength and aerobic capacity.

Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:

45 Years to 60 Years (Adult)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Criteria

Inclusion Criteria:

Age between 45-60

Ability to sign informed consent

Exclusion Criteria:

Subjects with cardiac abnormalities considered exclusionary by the study physicians

Subjects with uncontrolled metabolic disease

A GFR <65 mL/min/1.73m2 or evidence of kidney disease or failure

Subjects with vascular disease or risk factors of peripheral atherosclerosis

Any history of hypo- or hyper-coagulation disorders. (e.g., Coumadin use or history of DVT or PE)